Mediator for test sensor

Abstract

A method of forming a 3-phenylimino-3H-phenothiazine or a 3-phenylimino-3H-phenoxazine mediator includes providing a first reactant including phenothiazine or phenoxazine, providing a first solvent, providing a second reactant and providing a second solvent. The first reactant, first solvent, second reactant and second solvent are combined to form a reactants solution. Sodium persulfate is added to the reactants solution to couple the first and second reactants resulting in a reaction solution including the 3-phenylimino-3H-phenothiazine or the 3-phenylimino-3H-phenoxazine mediator.

What is claimed is: 
     
       1. A test sensor including a base, the base including an enzyme adapted to react with an analyte, and a mediator, the mediator having a background current being less than 200 nA after being exposed to a temperature of 50° C. for a duration of two weeks and further including a neutralizing agent, the neutralizing agent being present in an amount to obtain a pH in a range below 7 to about 5.5 in a mediator solution. 
     
     
       2. The test sensor of  claim 1  wherein the neutralizing agent is sodium hydroxide. 
     
     
       3. The test sensor of  claim 1  wherein the neutralizing agent is sodium bicarbonate. 
     
     
       4. The test sensor of  claim 1  further including a buffer. 
     
     
       5. The test sensor of  claim 4  wherein the buffer is sodium phosphate. 
     
     
       6. The test sensor of  claim 1  wherein the test sensor is an electrochemical test sensor. 
     
     
       7. The test sensor of  claim 1  wherein the test sensor is an optical test sensor. 
     
     
       8. The test sensor of  claim 1  wherein the mediator is a 3-phenylimino-3H-phenothiazine mediator. 
     
     
       9. The test sensor of  claim 1  wherein the neutralizing agent is sodium phosphate. 
     
     
       10. The test sensor of  claim 1  wherein the neutralizing agent is present in an amount to obtain a pH in a range below 7 to about 6 in the mediator solution. 
     
     
       11. The test sensor of  claim 1  wherein the neutralizing agent is present in an amount to obtain a pH of from about 5.5 to about 6 in the mediator solution. 
     
     
       12. A test sensor including a reagent, the reagent including a mediator and a neutralizing agent, the reagent having a % bias being within 2.4% between 0 and 400 mg/dL of glucose after being exposed to a temperature of 50° C. for a duration of two weeks, the neutralizing agent being present in an amount to obtain a pH in a range below 7 to about 5.5 in a mediator solution. 
     
     
       13. The test sensor of  claim 12  wherein the reagent includes a 3-phenylimino-3H-phenothiazine mediator. 
     
     
       14. The test sensor of  claim 12  wherein the reagent further comprises glucose dehydrogenase (GDH) and a cellulose polymer. 
     
     
       15. The test sensor of  claim 12  wherein the test sensor includes electrodes. 
     
     
       16. The test sensor of  claim 12  wherein the % bias is within 1.8% between 0 and 100 mg/dL of glucose after being exposed to a temperature of 50° C. for a duration of two weeks. 
     
     
       17. The test sensor of  claim 12  wherein the neutralizing agent is present in an amount to obtain a pH in a range below 7 to about 6 in the mediator solution. 
     
     
       18. The test sensor of  claim 12  wherein the neutralizing agent is present in an amount to obtain a pH of from about 5.5 to about 6 in the mediator solution. 
     
     
       19. A test sensor including electrodes and a reagent including glucose dehydrogenase (GDH), a mediator and a neutralizing agent, the reagent having a % bias being within 2.4% between 0 and 400 mg/dL of glucose after being exposed to a temperature of 50° C. for a duration of two weeks, the neutralizing agent being present in an amount to obtain a pH in a range below 7 to about 5.5 in a mediator solution. 
     
     
       20. The test sensor of  claim 19  wherein the reagent further includes 3-phenylimino-3H-phenothiazine mediator and a cellulose polymer. 
     
     
       21. The test sensor of  claim 19  wherein the % bias is within 1.8% between 0 and 100 mg/dL of glucose after being exposed to a temperature of 50° C. for a duration of two weeks. 
     
     
       22. The test sensor of  claim 19  wherein the neutralizing agent is present in an amount to obtain a pH of from about 6 to about 7 in the mediator solution. 
     
     
       23. The test sensor of  claim 19  wherein the neutralizing agent is present in an amount to obtain a pH of from about 5.5 to about 6 in the mediator solution. 
     
     
       24. A test sensor including a base, the base including an enzyme adapted to react with an analyte, and a 3-phenylimino-3H-phenothiazine mediator, the 3-phenylimino-3H-phenothiazine mediator having a background current being less than 200 nA after being exposed to a temperature of 50° C. for a duration of two weeks and further including a neutralizing agent, the neutralizing agent being present in an amount to obtain a pH in a range below 7 to about 6 in a mediator solution. 
     
     
       25. The test sensor of  claim 24  wherein the neutralizing agent is present in an amount to obtain a pH of from about 5.5 to about 6 in the mediator solution. 
     
     
       26. The test sensor of  claim 24  wherein the neutralizing agent is sodium hydroxide. 
     
     
       27. The test sensor of  claim 24  wherein the neutralizing agent is sodium bicarbonate. 
     
     
       28. The test sensor of  claim 24  wherein the neutralizing agent is sodium phosphate. 
     
     
       29. The test sensor of  claim 24  further including a buffer. 
     
     
       30. The test sensor of  claim 29  wherein the buffer is sodium phosphate. 
     
     
       31. The test sensor of  claim 24  wherein the test sensor is an electrochemical test sensor. 
     
     
       32. The test sensor of  claim 24  wherein the test sensor is an optical test sensor. 
     
     
       33. A test sensor including a base, the base including an enzyme adapted to react with an analyte, and a 3-phenylimino-3H-phenothiazine mediator, the 3-phenylimino-3H-phenothiazine mediator having a background current being less than 200 nA after being exposed to a temperature of 50° C. for a duration of two weeks and further including a neutralizing agent, the neutralizing agent being present in an amount to obtain a pH of about 6.1 in a mediator solution. 
     
     
       34. The test sensor of  claim 33  wherein the neutralizing agent is sodium hydroxide. 
     
     
       35. The test sensor of  claim 33  wherein the neutralizing agent is sodium bicarbonate. 
     
     
       36. The test sensor of  claim 33  wherein the neutralizing agent is sodium phosphate. 
     
     
       37. The test sensor of  claim 33  further including a buffer. 
     
     
       38. The test sensor of  claim 37  wherein the buffer is sodium phosphate. 
     
     
       39. The test sensor of  claim 33  wherein the test sensor is an electrochemical test sensor. 
     
     
       40. The test sensor of  claim 33  wherein the test sensor is an optical test sensor.